Picosecond acoustics in single quantum wells of cubic GaN/(Al,Ga)N

A picosecond acoustic pulse is used to study the photoelastic interaction in single zinc-blende GaN/AlxGa1−xN quantum wells. We use an optical time-resolved pump-probe setup and demonstrate that tuning the photon energy to the quantum well’s lowest electron-hole transition makes the experiment sensitive to the quantum well only. Because of the small width, its temporal and spatial resolution allows us to track the few-picosecond-long transit of the acoustic pulse. We further deploy a model to analyze the unknown photoelastic coupling strength of the quantum well for different photon energies and find good agreement with the experiments

Quantitative trait loci for bone traits segregating independently of those for growth in an F-2 broiler X layer cross

An F broiler-layer cross was phenotyped for 18 skeletal traits at 6, 7 and 9 weeks of age and genotyped with 120 microsatellite markers. Interval mapping identified 61 suggestive and significant QTL on 16 of the 25 linkage groups for 16 traits. Thirty-six additional QTL were identified when the assumption that QTL were fixed in the grandparent lines was relaxed. QTL with large effects on the lengths of the tarsometatarsus, tibia and femur, and the weights of the tibia and femur were identified on GGA4 between 217 and 249 cM. Six QTL for skeletal traits were identified that did not co-locate with genome wide significant QTL for body weight and two body weight QTL did not coincide with skeletal trait QTL. Significant evidence of imprinting was found in ten of the QTL and QTL x sex interactions were identified for 22 traits. Six alleles from the broiler line for weight- and size-related skeletal QTL were positive. Negative alleles for bone quality traits such as tibial dyschondroplasia, leg bowing and tibia twisting generally originated from the layer line suggesting that the allele inherited from the broiler is more protective than the allele originating from the layer

Sustratos y frecuencias de riego óptimos para el crecimiento de plantas de mandarino Cleopatra (Citrus reshni Hort. ex Tan) para porta-injertos

Plantas jóvenes de mandarino Cleopatra (Citrus reshni Hort. ex Tan.) son frecuentemente utilizadas como porta-injertos en plantaciones comerciales.Para el cultivo de estas plantas se emplean importantes cantidades anuales de suelo de monte. Esto conduce a deteriorar los ambientes de origen, afectando su sustentabilidad por la descontrolada erosión que producen.Se propone identificar sustratos alternativos para la obtención de plantines porta-injertos comerciales y determinar una frecuencia de riego con solución nutritiva más efectiva para dicha finalidad.Del análisis de los resultados surge que, para cultivar plantines de mandarino Cleopatra y obtener el diámetro de injertación de 0,50 cm en el menor tiempo, es posible utilizar arena + turba 50:50 regando día por medio con solución nutritiva según UC System. Esta mezcla puede sustituir de manera efectiva al suelo de monte actualmente empleado en viveros

Solid-state 27 Al MRI and NMR thermometry for catalytic applications with conventional (liquids) MRI instrumentation and techniques

Multidimensional images of Al2O3 pellets, cordierite monolith, glass tube, polycrystalline V2O5 and other materials have been detected by 27Al, 51V, and 23Na NMR imaging using techniques and instrumentation conventionally employed for imaging of liquids. These results demonstrate that, contrary to the widely accepted opinion, imaging of ¿rigid¿ solids does not necessarily require utilization of solid state NMR imaging approaches, pulse sequences and hardware even for quadrupolar nuclei which exhibit line widths in excess of 100 kHz, such as 51V in polycrystalline V2O5. It is further demonstrated that both 27Al NMR signal intensity and spin-lattice relaxation time decrease with increasing temperature and thus can potentially serve as temperature sensitive parameters for spatially resolved NMR thermometry